Ankle sprains are among the most common injuries sustained in sports. Up to 40 percent of all athletic injuries are related to ankle sprains. Despite its high incidence and potential for morbidity, there is no agreed-upon standard for ankle sprain treatment.

Increased youth sports participation, encouragement by medical professionals to engage in fitness activities for health, and baby boomer weekend warriors looking to recapture the glory days, all contribute to the exposure to potential injury and the high incidence of ankle sprains.

Injury rates are greatest in sports that involve rapid changes of direction, jumping, running and cutting. Injury rates can reach as high as 50 percent in basketball players and 29 percent in soccer players.¹

How it Happens

The typical mechanism of injury for lateral ankle sprains is forced plantar flexion and inversion of the ankle, usually with the body's center of gravity displaced outside the base of support. The most common anatomic sites injured are the lateral ankle ligaments (anterior talofibular ligament, calcaneofibular ligament and posterior talofibular ligament).

The anterior talofibular ligament helps prevent anterior translation and internal rotation of the talus, while the calcaneofibular ligament stabilizes the ankle and prevents talar tilt as the ankle moves from neutral into dorsiflexion. Damage to either, or both, could result in abnormal anterolateral motion of the talus, which is defined as ankle instability.

While the majority of ankle injuries involve the lateral ligamentous complex, most do not develop instability. Those that end up being unstable are usually believed to have an accompanying loss of mechanoreceptor function. Classified as either mechanical or functional, the concern with chronic ankle instability is that unbalanced loading and increased joint motion can lead to early degenerative changes. The potential end result of severe arthritis and pain is total ankle replacement or ankle fusion.

Addressing Functional Deficits

Ankle instability can be divided into two types: mechanical and functional instability. Mechanical instability is the abnormal laxity of the talocrural joint, resulting from damage to the ligamentous restraints. Functional instability is the subjective presence of pain and unreliability ("giving way"), even with the absence of increased joint laxity.

Treatment options for ankle instability vary and can range from physical therapy for strengthening weak muscles and retraining proprioception to surgical options for repair or reconstruction of the joint. Based on literature that suggests proprioceptive deficits or peroneal weakness as possible underlying factors, an initial conservative approach could be helpful in treating functional instability, especially in the absence of any mechanical and structural issues. A failed conservative approach might indicate the need to consider surgical alternatives to recreate stability in the ankle joint.

For conservative, pre-surgical and post-operative rehab, most authors advocate strengthening muscles around the ankle combined with well-timed proprioceptive exercises to restore proper ankle biomechanics and function.

Progressive Loading Techniques

Unstable, injured and post-surgical ankles can be difficult to rehab, however, as weight-bearing can aggravate the condition or delay healing. For this reason, clinicians are turning to modern technology to help.

One option are treadmills that offer an unweighting feature, either through a harness system, being submerged in a pool, or through differential-air-pressure (DAP) technology. DAP progressively loads patients by precisely controlling the level of weight-bearing through the lower-extremity joints.

Therapists can find the exact amount of body weight that will allow pain-free closed-kinetic-chain activity and help protect healing tissue while encouraging AROM and stimulation of proprioceptors. Users can engage in dynamic balance activities in a safe environment, thus restoring normal gait and running mechanics sooner. The large effective range of progressive loading, from 20- to 100-percent body weight, ensures that a wide range of patients, with a variety of diagnoses, can benefit.

Once supported in the treadmill, patients can perform any closed-chain activities inside the unit that they can outside. A patient in the early stages of ankle rehab may do squats, lunges, single-limb squats or calf raises at a reduced body weight. This activity modification encourages lower-extremity joint ROM without placing stress on the healing tissue in the ankle. At the same time, proprioceptors are stimulated, co-contraction of dynamic ankle stabilizers is facilitated, and gentle loading for cartilage and bone health is promoted.

As the patient gets more comfortable, gait training can begin at the same body-weight level that closed-kinetic-chain activities were tolerated. By keeping the load level the same, impact should not increase and tissue stress should not rise. The goal is restoration and maintenance of normal lower-extremity mechanics without pain.

Higher-level patients can perform more dynamic skills and activities. From proprioceptive challenges on a pad or disc, to multi-tasking activities like catching or throwing a ball, DAP can provide a safe environment to protect them from reinjuring the ankle while relearning these activities. Plyometric bounding activities can even be performed with reduced joint impact, allowing athletes to carefully resume sport-specific and functional training sooner in the rehab program. 

Reference

1. Smith, R., & Reischl, S. (1986). Treatment of ankle sprains in young athletes. The American Journal of Sports Medicine, 14(6), 465-471.

Jacon Chun is owner of Elite Sports Physical Therapy, with locations in Fremont and Dublin, CA, and clinical specialist for AlterG, makers of the Anti-Gravity Treadmill.

A 31-year-old male endurance athlete (triathlete and marathoner) was treated post-operatively for right ATF and CF reconstruction, peroneus longus repair and anterior talocrural joint debridement.

At four weeks post-op, the patient started a walking program on an air-pressurized unloading treadmill using differential air pressure (DAP) at 60 percent body weight, 1.5 mph and no incline. The focus was on proper gait mechanics and the patient was required to have pain rating of 2 or lower on the VAS.

During the next week (five), the patient was allowed to increase speed and duration on the anti-gravity treadmill to 2.5-3 mph for 20 minutes. The patient was allowed to increase body weight in 5 percent increments, as long as gait mechanics stayed normal and pain levels did not increase.

At week six, the patient was ambulating at 90 percent body weight, and was therefore allowed to start jogging at 70 percent body weight at 4.5 mph. Running speed and duration were increased in subsequent sessions, as long as no deviations were present and the pain level did not increase. By week eight post-op, the patient returned to running at full body weight with normal mechanics and no complaints of pain.

With the current focus on maximizing rehabilitation outcomes, the ability to combine closed-kinetic training with proprioceptive re-education earlier in the recovery process is important for those diagnosed with ankle instability.

Proper application of these rehabilitation principles, with the assistance of DAP technology, can potentially help some avoid surgery, as well as ensure that those requiring ankle stabilization achieve a favorable end result.

Matt Kraemer, PT, DPT, ATC, CSCS, is clinical director at Endurance Rehabilitation in Phoenix, AZ.